Code calling system



June 2, 1936.

POWER FMCW P. 0. SMITH 2,042,869

CODE CALLING SYSTEM Filed Jan. 23, 1935 2 Sheets-Sheet l C ODE SIGNALINGlNVE/VTOR P. C. SMITH A TTORNEV Jul/1e 1935- P. c. SMITH 2,

CODE CALLING SYSTEM Filed Jan. 23, 1935 2 Sheets-Sheet 2 CODE SIGNALINGCIRCUIT POWER PACK FIG. 2

INVENTOR R 6. SMITH ATTORNEY Patents June 2, 1935 UNITED STATES PATENTOFFICE CODE CALLING SYSTEM Application January 23, 1935,- Serial No.2,980

13 Claims.

This invention relates to a signaling system and more particularly tocode signaling arrangements whereby certain persons may be reached whenthey are absent from their offices on business in other departments of astore, factory or other business establishment.

The object of the invention, generally stated. is the provision of newand improved circuit arrangements whereby code signals may betransmitted efliciently and with less apparatus than has been heretoforenecessary.

The code signaling system in accordance with the present invention isadapted for use in conjunction With a private branch exchange system andparticularly with a system installed in business establishments, such asstores and factories. When the operator receives a call for a particularofficial, such as a superintendent or foreman, and upon establishing theusual telephone connection to his substation receives no response, shemay, if the .call is urgent, signal the desired person over a codesignaling circuit. The code signaling circuit extends through theestablishment and has connected thereto, at strategic points, signalbells or other announcing means. When the operator connects with thesignaling circuit she causes signals to be transmitted thereover inaccordance with a predetermined code thereby operating all of the signalbells associated with the signaling circuit in accordance with thetransmitted code. The desired oflicial, if he is in any department ofthe establishment where one of the signal bells is located, hearing hisparticular code rung will then return to his own substation or to thenearest telephone substation to answer the incoming call.

The present invention relates particularly to a sending circuit by meansof which an operator may transmit any one of a plurality ofpredetermined codes of signals over the signaling circuit. According toone modification of the invention, the sender comprises a bank oflocking keys comprising as many keys as there are codes which may besent, certain of the keys being arranged for controlling thetransmission of single digit codes while others are arranged forcontrolling the transmission of two-digit codes. Associated with thekeys is a start key and a group of condensers serving as registers. Whenany key is operated followed by the operation of the start key, initialcharges are placed on the register condensers, the charges on one ormore of the condensers being commensurate with the digital value of thecode digit or digits for which the particular key is wired. Charges arealso placed on the remaining condensers commensurate with the length ofdigit spacing and code spacing intervals which are to be introducedbetween the transmission of successive series of impulses to thesignaling circuit.

For generating impulses for transmission over the signaling circuit, animpulsing relay is provided which may be operated by any suitableinterrupting means operating at a predetermined rate. This interruptingmeans may be of any well-known type although for the purposes ofillustration an interrupter circuit employing a gas-filled tube of thetype disclosed in Patent No. 1,979,054 granted October 30, 1934 to W. H.Scheer has been shown. The impulsing relay in addition to transmittingimpulses over the signaling circuit also controls an impulse countingarrangement for counting the number of impulses in each seriestransmitted and for counting impulses for determining the spacingintervals. The impulse counting arrangement comprises a gas-filled tubewhich may be of the three-element type filled with an inert gas such ,7as neon, argon, helium, mercury vapor or combinations of gases of thisclass and which breaks down or ionizes when the potential on its controlor grid element is raised sufficiently above a critical value, asecondary condenser and a train of anode or stop relays. This countingarrangement functions with the impulsing relay and register condensersin much the same manner as disclosed in Patent No. 2,002,219, grantedMay 21, 1935 to T. L. Dimond, except that the anode I relays also serveas a steering switch for associating the register condenserssuccessively with the tube during the sending of codes of impulses.

The start key has three positions, a normal or w non-operate position, aleft start position for starting the sender for transmitting any singledigit code of impulses and a right start position 40 for starting thesender for transmitting any twodigit code of impulses.

In general, the sender functions in the following manner: If it beassumed that the key for the two-digit code 4I is operated and the startkey is then operated to the right, an initial charge is placed on thefirst register condenser of a value which is the complement of the valueof the first digit 4 of the code, that is, six increments of charge areplaced thereon, an initial charge is placed on the second registercondenser which is the complement of the digital value of the digitspacing interval, an initial charge is placed on the third registercondenser which is the complement of the second digit I of the code,that is,

nine increments of charge are placed thereon, and an initial charge isplaced on the fourth register condenser which is the complement of thedigital value of the code spacing interval. A slow-to-operate relay thenoperates to isolate the condensers from their charging circuits and tothen start the interrupter to cause the periodic operation and releaseof the impulsing relay and the charging and discharging of a secondarycondenser.

The grid of the tube of the counting circuit is at this time connectedwith the first registering condenser over back contacts of the first ofthe train of anode relays. The anode of the tube is connected throughthe winding of the first anode relay to a source ofpositive potentialand ing condenser. The secondary condenser is associated with contactsof the impulsing relay so that it becomes charged to a definitepotential each time that the impulsing relay releases and becomesconnected into a discharging circuit each time that the impulsing relayoperates. Upon the first operation of the impulsing relay to transmitthe first impulse over the signaling'circuit, the charged secondarycondenser discharges into the first registering condenser thus raisingits potential by a predetermined increment and consequentiy raising thepotential on the grid of the tube by the same increment Upon thesubsequent releases and operations of the impulsing relay this cycle ofoperations is repeated to add further increments of potential to theassociated register condenser until such condenser has received fourincrements or'has a total of ten increments of potential, at which timethe potential on the grid of the tube will have been raised to such anextent that the tube will flash and operate the first anode relay. Theimpulsing relay will thus have transmitted a series of four relay of thetrain, connects the winding of the second'anode relay to the anode ofthe tube and transfers the circuit of the grid of the tube from thefirst to the second registering condenser. The sender is now conditionedfor measuring off a delay interval prior to the transmission of thesecond digit series of the code.

With the grid of the tube now connectedto the second registeringcondenser the grid is. raised to the potential of this second condenserand in the previously described manner the potential of the secondcondenser is raised by increments and consequently the potential of thegrid of the tube is raised by the continued operation of the impulsingrelay imtil the condenser has. been charged to ten increments ofpotential'at which time the potential on the grid of the tube will havebeen raised to such an extent that the tube will flash and operate thesecond anode relay. A digit spacing interval has thus been measured oif,the length of-which has been determined by the amount of the initialpotential on the second registering condenser. Since, however, thesignaling circuit was opened by the operation of the first anode relay,the impulse relay has not been instrumental in transmitting furtherimpulses over the signaling circuit. 1

The second anode relay upon operating functions to deionize the tube, tolock itself operated under the control of the last anode relay of thetrain, to prepare a new anode circuit from the anode of the tube throughthe winding of the third anode relay, to reestablish the signalingcircuit and to transfer the connection ofthe grid of the tube from thesecond to the third regisl0 tering condenser. The sender is nowconditioned for transmitting a series of impulses in accordance with thesecond digit of the keyed code, I which series of impulses .istransmitted and counted in the same manner as the first series. 15 I Ithaving been assumed that the third condenser had an initial charge ofnine increments,

the potential on the grid of the tube will be raised to such a-potentialas to cause the tube to flash after one impulse has been transmitted andone increment of potential has been added to the third condenser. Whenthe tube flashes the third anode relay operates and functions todeionize the tube, lock itself operated under the control of the lastanode relay of the train, to prepare a 25 new anode circuit from theanode to the winding of the last anode relay, to open the signalingcircult and to transfer the connection of the grid of the tube from thethird to the fourth registering condenser. The sender is now conditioned39 for measuring off a delay interval prior to the Y repetition of thefirst digit of the code.

The counting circuit now functions in the manner previously described tocount off a delay in- M terval as determined by the initial charge onthe fourth registering condenser but the signaling circuit being openthrough the operation of the third anode relay, no impulses aretransmitted over the signaling circuit. "miin the impulse relay hascaused the addition of suflicient in-- 4 crements of potential to thefourth condenser to raise its total potential to ten increments, thetube flashes and operates the last anode relay which deionizes the tube,momentarily locks, and unlocks the other anode relays. With the first 5anode relay released the grid of the tube is again connected to thefirst condenser, the anode is connected through the winding of the firstanode relay and the signaling circuit is reestablished.

If the start key is still operated the circuits function in the samemanner to repeat the transmission of the code impulses so long as thestart key remains operated.

The senderfunctions in much the same manner to transmit a single digitcode except that 5 with the start key operated to the left the firstanode relay upon operating to terminate the transmission of-the firstorsingle digit series transfers the grid of the tube from the first tothe fourth condenser and transfers the anode circuit of the tube to thewinding of the last anode relay whereby the functions performed by thesecond and third anode relays are omitted and y a code spacing delay ismeasured immediately following the transmission of the single digitseries. 65

A second modification ofth'e invention is disclosed which functions inasimilar manner, the chief difierence residing in the fact that two rowsof keys are provided, the keys of one row being operated for any one often single digit codes 70 and the keys in eachrow being operated for any.of a plurality of two-digit codes thus enabling a tailed descriptiontaken in connection with the drawings:

Fig. 1 shows one embodiment of the invention comprising a single row ofdigit keys and impulse transmitting mechanism; and

Fig. 2 shows a second embodiment of the invcntion comprising two rows ofdigit keys and impulse transmitting mechanism.

The keys of the key-set of Fig. 1 are of the locking type, any depressedkey remaining in its operated position until another key is operated.Ten keys are disclosed six of which control the transmission of the sixsingle digit codes I to 6, inclusive, and four of which control thetransmission of two-digit codes 2--I, 3--I, 4I and 3--2. Other keysobviously might be added to control the transmission of further singleand two-digit codes.

The keys of the key-set of Fig. 2 are also of the lockingtype, anyoperated key of either vertical.

row remaining in its operated position until another key of the same rowis operated. Ten keys are provided in each row, any key of the left-handrow being operated alone for any one of ten single digit codes and a keyin each row being oper ated for any desired two-digit code. The startkey ST of each figure is of the three-position type, its mid-positionbeing a non-operate position, its left position being an operateposition for starting the circuit for transmitting any single digit codeof impulses and its right position being an operate position forstarting the circuit for transmitting any two-digit code of impulses.

The rectangles indicated by the numerals I and 200 of Figs. 1 and 2represent power-packs of any well-known type capable of takingalternating current from a power outlet and tr'ansforming it into directcurrent of the proper voltages and polarity for supplying operatingcurrent to the apparatus of the sender. The tubes I40 and I50 of Fig. 1and the tubes 240 and 250 of Fig. 2 are of the hot cathode, gas-filledtype each having a cathode heated conductively from a filament, acontrol electrode or grid, and an anode.

In each figure the code signaling circuit to which code impulses areapplied has been only indicated, it being understood that this circuitwould be extended throughout the ofiice, store or factory which theimpulse sender serves, and supplied at strategic points with the usualbells or signaling devices. The impulses are transmitted to the codesignaling circuit of Fig. 1 by impulse relay I30 under the control ofthe gaseous tube interrupter including tube I40 and similarly, impulsesare transmitted to the code signaling circuit of Fig. 2 by impulse relay230 under the control of the gaseous conductor tube interrupterincluding tube 240. These interrupter circuits are of the type disclosedin the patent to Scheer hereinbefore referred to. It will, of course, beobvious that any other well-known type of interrupter could be used withequal facility.

The invention will first be described in connection with Fig. 1, itbeing assumed that the operator desires to call a person whose code callnumthe first anode relay II4 and the inner upper normal contacts thereofto the anode of tube I50 thus applying positive anode potential to theanode of this tube. The lower terminal of the voltage divider and theupper terminals of condensers I20, I2I, I22 and I23 are connected to thenegative bus-bar I I8 extending from the power-pack I00.

With the key II9 operated, the lower terminal of condenser I20 isconnected over the outer left back contact of relay I24, inner upperright alternate contact of key ST, left contacts of key I I9 to a pointon the voltage divider between resistances I06 and I0'I wherebycondenser I20 is charged to a potential equal to the. drop of potentialacross the six resistances N! to H2, inclusive, or is charged with sixincrements of potential. The lower terminal of condenser I2I isconnected over the inner left back contact of relay I24 to a point onthe voltage divider between resistances I04 and I whereby condenser I2Iis charged to a potential equal to the drop of potential across theeight resistances I05 to H2, inclusive, or is charged with eightincrements of potential. The lower terminal of condenser. I22 isconnected over the inner right back contact of relay I24, the lowerright alternate contacts of start key ST, the right contacts of key II9to a point on the voltage divider between resistances I03 and I04whereby condenser I22 is charged to a potential equal to the drop ofpotential across the nine resistances I04 to H2, inclusive, or ischarged with nine increments of potential. The lower terminal ofcondenser I23 is connected over the outer right back contact of relayI24 to a point on the voltage divider between resistances I01 and I08whereby condenser I23 is charged to a potential equal to the drop ofpotential across the five resistances I08 to H2, inclusive, or ischarged with five increments of potential. Thus, condensers I20 and I22assume charges commensurate with the complements of the digital valuesof the digits 4 and I. Condenser I2I assumes a charge commensurate withthe complement of the digital value of the digit spacing interval whichis, in the case assumed, equal to the period required to produce twoimpulses and condenser I23 assumes a charge commensurate with thecomplement of the digital value of a code spacing interval which, in thecase assumed, is

equal to the period required to produce five impulses. It will, ofcourse, be obvious that the digit spacing and code spacing intervals maybe made of any required value by varying the initial charges ofcondensers I2I and I23 through the connection of their upper terminalsto different points on the voltage divider comprising resistances I03 toH2, inclusive.

The operation of start key ST also establishes a circuit for relay I24extending from the positive bus-bar IOI, over the upper right contactsof key ST, winding of relay I24, lower back contact of relay I H to thenegative bus-bar I I8, relay I24 locking over its left front contact tothe positive bus-bar IOI independent of start key ST and remainingoperated over this locking circuit until pulsing is completed for asingle transmission of the keyed digit code. Relay I24 being slow tooperate does not operate immediately when the key ST is operated thusallowing a sufficient interval for condensers I20 to I23, inclusive, tobecome charged. When it finally operates, it opens at its back contacts,the initial charging circuits for these condensers and at its outerright contacts connects positive potential from the positive bus-bar IOIover t he upper right contacts to key ST to conducto r I23 for startingthe gaseous tube interrupter.

The application of positive potential to conductor I28 charges condenserI33 in a circuit extending from conductor I28, upper back contact ofpulsing relay I30, condenser I33, resistance I34 to the negative bus-barII3; applies positive potential to the anode of tube I40 over theadjustable resistance I29, the lower back contact and winding of relayI30 and adjustable resistance I3I;,and charges. condenser I32 in acircuit extending from conductor I28, resistance I20, lower back contactof relay I30, condenser I32 voltage divider I21 to the negative bus-barH3. The voltage divider I21 is bridged between conductor I28 and thenegative bus-bar H3 and is so adjusted that the potential between thebnode and cathode of tube I40 is less than that required to-ionize thegaseous content of the tube. The

cathode of tube I 40- is heated conductively from the filament which isconnected by conductors I25 and I26 to the filament current supply ofpower-pack I00. The control electrode or grid of the tube is connectedto the negative bus-b II8 through resistance I35.

When condenser I32 becomes charged to a potential equal to theioniza'tionpotential of tube I40, tube I40 ionizes and becomesconducting causing condenser I32 to discharge in :a circuit through thewinding of relay I30, adjustable resistance I 3| to the negative bus-barII 8 through the anode and cathode of tube I40, thereby operating relayI30. Relay I upon operating opens the charging circuit for condenser I32at its lower back contact and remains operated until the potentialacross the plates of condenser I32 falls suflicientlybelow theionization potential of tube I to cause the tube to be deionized and.become non-conducting. With tube Mil-deionized the discharge circuit ofcondenser I32 is opened and relay I30 releases. When relay I30 releasesthe previously traced charging circuit for condenser I32 is againclosed. When relay I30 operated it also connected the condenser I33 intoa discharge path and closed one point in the tip conductor I36 of theoutgoing code signalingcircuit for a purpose to be later described. Uponthe release of relay I 30' the charging circuits of condensers I32 andI33 are again established and the tip conductor I36 of the signalingcircuit is opened.

The above cycle of operations, namely charging condensers I32 and I33,ionizing tube I40, discharging condensers I32 and I33, deionizing tubeI40, and operating and releasing relay I30 continues as long as positivepotential is applied to conductor I28 through the operation of relayI24. The periodic operation and release of relay I30 causes the periodicopening and closing of the signaling circuit to produce impulsesthereover; The periodicity of the impulses so generated may becontrolled by varying the capacitance of condenser I32 and the chargingand discharging rate thereof. The discharge rate of condenser I32 iscontrolled by adjustable resistance I3I and, since relay I 30 operatesin the discharge circuit of condenser I32, the adjustment of resistanceI 3 I, determines the time interval during which relay I30 is maintainedoperated and the interval dur- 'ing which the signaling circuit ismaintained closed. The charging rate of condenser I32 is controlled byadjustable resistance I29 and since relay I30 does not operate until thecharge on condenser I32 is suflicient to cause tube I40 to ionize, theadjustment of resistance I23 determines the time interval during whichrelay I30 remains released and therefore the intervals betweensuccessive impulses transmitted over the signaling circuit. 5

Upon the first operation. of pulsing relay I30 following the depressionof start key ST, the signaling circuit is closed from the tip conductorI36 over the lower front contact of relay I30, the lower back contact ofanode relay II4 to the ring conductor I31 thereby causing thetransmission of one impulse over the signaling circuit. At the same timecondenser I33 is connected into a discharge circuit extending over theupper front contact of relay I30, the upper back contact of anode relayII4, through condenser I20, negative bus-bar II3 resistancel34 andcondenser I33. Condenser I33 thereupondischarges into condenser I20adding an increment of charge to the six increments of initial chargepreviously applied to condenser I20. 0n its'next release relay I30causes the recharging of condenser I33 and the opening of the signalingcircuit thus terminating the first impulse. I

Upon the subsequent energizations of relay I30 additional closures ofthe signaling circuit result in the transmission of further impulses andfurther increments of charge are added to condenser I20 by the dischargeof condenser I33 thereinto until condenser I20 becomes fully charged, atwhich time four impulses will have been transmitted to the signalingcircuit. The potential on the grid of tube I50 will now be renderedsumciently positive by the application of potential thereto from thelower terminal of condenser I20 over the upper back contact of anoderelay II4, to cause tube I50 to ionize since its cathode is suppliedwith negative potential from the bus-bar II 8, its anode is suppliedwith positive potential over the circuit previously traced and itscathode 40 is heated conductively by the filament which is connected tothe filament supply conductors I25 and I26. Condenser I20 discharges ina path from its upper terminal over the cathode and. grid of tube I50,upper back contact of relay H4 to the lower terminal of the condenser.

When tube I ionizes current flows in its cathode-anode circuit from thenegative bus-bar II8, cathode and anode of the tube, inner upper normalcontacts and winding of anode relay II4, 5O conductor I I3, thence astraced to the positive bus-bar IOI. Relay II4 operates in this circuitfirst locking in a circuit from conductor II3 through its winding andmiddle upper front contact, lower back contact of relay I I1 to thenegative bus-bar IIB, then opening the cathode-anode circuit of tube I50at its inner upper back contact thereby deionizing tube I50 and finallyconnecting the anode of tube I50 over its inner upper front contact, theinner upper left normal contacts of key ST, the inner upper normalcontacts and winding of anode relay I I5 to conductor H3 and thence tothe positive bus-bar IOI. At its upper back contact relay II4disconnects the grid of tube I50 and the discharge circuit of condenserI33 from the lower terminal of condenser I20 and connects the grid oftube I50 and the discharge circuit of condenser I33 over the upper frontcontact of relay II4, the inner lower left normal contacts of key ST,the upper back contact of "9 anode relay II5 to the lower terminal ofcondenser I2I. Tube I 50 is now prepared for response to the counting ofthe digit spacing interval as determined by. the initial charged contionof condenser I2I. Relay II4 also opens the signaling circuit at itslower back contact thereby preventing the transmission of furtherimpulses over the signaling circuit through the continued operation ofimpulsing relay I30 during the counting of the digitspaclng interval.Thus, the operation of relay I30 in conjunction with tube I50 hasresulted in the transmission of four impulses over the signalingcircuit.

As relay I30 continues to operate and release under the control of tubeI40, condenser I33 is periodically charged and discharged, but noimpulses are transmitted over the signaling circuit since this circuitis open at the lower back contact of relay III. The discharge circuit ofcondenser I33 now extends over the upper front contact of relay I30,thence as traced to the lower terminal of condenser I2I and from theupper terminal of condenser I2I, over bus-bar II8, resistance I34 tocondenser I33. Upon each discharge of condenser I33 into condenser I2Ian increment of charge is added to condenser I2I until when twoincrements have been added, condenser I 2 I, which as will be recalledwas initially charged with eight increments of charge, will become fullycharged. The potential on the grid of tube I50 will now be suflicientlypositive to permit tube I50 to ionize and operate anode relay H5 in itscathode-anode circuit. Condenser I2I discharges through tube I50.

Relay II5 upon operating first locks in a cir cuit extending fromconductor II3 through its winding and upper middle front contact, backcontact of relay I I! to negative bus-bar I I8, then opens thecathode-anode circuit of tube I50 at its inner upper back contactthereby deionizing tube I50, and finally connects the anode of tube I50over the inner upper front contact of relay I I4, inner upper leftnormal contacts of key ST, inner upper front contact of relay II5, innerupper back contact and winding of anode relay II6, conductor II 3 andthence to the positive bus-bar I0 I. At its upper back contact relay II5 disconnects the grid of tube I50 and the discharge circuit ofcondenser I 33 from the lower terminal of condenser I2I and connects thegrid of tube I50 and the discharge circuit of condenser I33 over theupper front contact of relay II4, the inner lower left normal contactsof key ST, the upper front contact of relay I I5, the upper back contactof relay I I6, to the lower terminal of condenser I22. Tube I50 is nowprepared for response to the counting of the second digit of the code asdetermined by the initial charged condition of condenser I22. Relay II5also recloses the signaling circuit at its lower front contact therebypermitting the transmission of further impulses over the signalingcircuit through the continued operation of impulsing relay I30.

As relay I30 continues to operate and release under the control of tubeI40 it, upon each operation, closes the signaling circuit which nowextends from conductor I36, lower front contact of relay I30, lowerfront contact of relay II5, lower back contact of relay II6 to conductorI31 and, at its upper contact, causes the periodic charging anddischarging of condenser I33. The discharge circuit of condenser I33 maynow be traced over the upper front contact of relay I30, the upper frontcontact of relay H4, thence as traced to the upper front contact ofrelay II5, upper back contact of relay II6, through condenser I22,negative bus-bar H8, resistance I34 to condenser I 33. Upon the firstdischarge of condenser I33 into condenser I22 an increment of charge isadded to the nine increments of charge which, it will be recalled, wereinitially placed in condenser I22 thus fully charging this condenser.The potential on the grid of tube I50 will now be sufliciently positiveto permit tube I50 to ionize and operate anode relay H6 in itscathode-anode circuit previously traced. Condenser I22 now dischargesthrough tube I50.

Relay II6 upon operating first locks in a circuit extending fromconductor II3 through its winding and upper middle front contact, lowerback contact of relay I H to negative bus-bar I I8, then opens thecathode-anode circuit of tube I50 at its inner upper back contactthereby deionizing tube I50, and finally connects the anode of tube I50over the circuit previously traced to the inner upper front contact ofrelay I I5, the inner upper front contact of relay IIG, the inner uppernormal contacts and winding of anode relay II'I, conductor I I3 andthence to the positive bus-bar IOI. At its upper back contact relay II6disconnects the grid of tube I50 and the discharge circuit of condenserI33 from the lower terminal of condenser I22 and connects the grid oftube I50 and the discharge circuit of condenser I33 over the upper frontcontact of relay II4, thence as traced to the upper front contact ofrelay II5, the upper front contact of relay IIB, the upper back contactof relay I IT to the lower terminal of condenser I23. Tube I50 is nowprepared for response to the counting of the code aspacing interval asdetermined by the initial charged condition of condenser I 23. Relay II6also opens the signaling circuit at its lower back contact therebypreventing the transmission of further impulses over the signalingcircuit through the continued operation of impulsing relay I30 duringthe counting of the code spacing interval. Thus, the operation of relayI30 in conjunction with tube I50 has resulted in the transmission of asingle impulse over the signaling circuit.

As relay I30 continues to operate and release under the control of tubeI40 it causes the periodic charging and discharging of condenser I33,but does not transmit impulses over the signaling circuit since thiscircuit is open at the lower back contacts of relays H4 and II B. Thedischarge circuit of condenser I33 may now be traced over the upperfront contact of relay I30, the upper front contact of relay II4, thenceas traced to the upper front contact of relay IIB, upp r back contact ofrelay 1, through condenser I23, negative bus-bar II8, resistance I34 tocondenser I33. Uponeach discharge of condenser I33 into condenser I23 anincrement of charge is added' to the five increments of charge which, itwill be recalled, were initially placed in condenser I23. When five suchincrements have been added the potential on the grid of tube I50 will besufficiently positive to permit tube I 50 to ionize and operate anoderelay I IT in its cathode-anode circuit, previously traced. CondenserI23 discharges through tube I50.

Relay II'I upon operating first locks in a circuit extending fromconductor II3 through its winding and inner upper front contact, theinner right front contact of relay I24 to the negative bus-bar H8 andthen opens the cathode-anode circuit of tube I50 at its inner upper backcontact thereby deionizing tube I50. At its lower back contact relay II1opens the locking circuits of will be immediately recharged 'withinitial charges as determined by the operated'key IIS and relay I24 willthereafter operate to start the sender to repeat the cycle of operationspreviously de-' scribed. Thus, so long as the key H3 and start key STremain operated, the code signal 4-|I will be repeatedly transmitted,the digits 4 and I being spaced by a short spacing interval andsuccessive repetitions of the code 4I being spaced by a longer codespacing interval. When the operator desires to terminate thetransmission of the code call,.she will restore key ST to its normal ormiddle position thus opening-the initial operating circuit of relay I24.As soon as, pulsing is' completed for the transmission of the code 4-Iand relay III operates, relays H4, H5 and H6 will release and thelocking circuit of relay I24 will be opened. Relay I24 will release inturn causing the release of relay III and the stopping of the gaseoustube interrupter.

It will now be assumed that. the operator desires to transmit the singledigit code 2 and therefore first operates the key I38 followed by theoperation of' start key ST to the left. With key I38 operated, the lowerterminal of condenser I20 is connected over the outer left back contactof relay I24, lower alternate left contacts of key ST, contacts of keyI38 to a point on the voltagedivider between resistances I04 and I05whereby condenser I20 is charged to a potential equal to the 'drop ofpotential across the eight resistances I05 to H2, inclusive or ischarged with eight increments of potential. Condenserv I2I is chargedover the circuit previously traced with eight increments of potentialand condenser I23 is charged over the circuit previously traced withfive increments of potential. There is no charging circuit for condenserI22 with the start key ST operated to the left, and therefore thiscondenser remains uncharged. Thus, condenser I20,

'- assumes a charge commensurate with the complement of the digit valueof digit 2 and condenser I23 assumes a charge commensurate with thecomplement of the digital value of a code spacing interval which, in thecase assumed, is

equal to the period required to produce five impulses. The charging ofcondenser I2I is withmission of one impulse over the signaling circuit.

At the same time condenser I33 is connected into a discharge circuitextending overfthe upper front contact of relay I 30, the upper backcontact of anode relay II4, through condenser I20, negative bus-bar II8,resistance I34 and condenser I33. Condenser I33 thereupon dischargesinto condenser I20 adding an increment of charge to the eight incrementsof initial charge previously applied to condenser I20. On its nextrelease relay I30 causes the recharging of condenser I33 and the openingof the signaling circuit. Upon the next energization of relay I30 9.second impulse is transmitted over the signaling circuit and a secondincrement of charge is added to condenser I20 by the discharge ofcondenser I33 therethrough. Condenser I20 is now fully charged and thepotential of tube I50 hasnow been rendered sumciently positive, by theapplication of potential thereto from the lower terminal of condenserI20 over the upper back contact of relay I I4 to cause tube I 50 toionize. 1

When tube I50 ionizes current flowsin it's cathode-anode circuit fromthe negative bus-bar II8, cathode and anode of the tube, inner uppernormal contacts and winding of anode relay I I4, conductor II3,'upperleft alternate contacts of key 10 ST to the positive bus-bar IOI.Condenser I20 discharges through tube I50. Relay II4 operates in thiscircuit first locking in a circuit from conductor II3 through itswinding and middle upper front contact, lower back contact of relay 1 15to the negative bus-bar IIO, then opening the cathode-anode circuit oftube I50 at its inner upper back contact thereby deionizing tube I 50',and flnally connecting the anode of tube I50 over the inner upper front.contact of 'relay II4, the 20 inner upper alternate contacts of' key ST,the

inner upper normal contacts and winding of anode relay II'! to conductorH3 and thence to the positive bus-bar IOI. At its upper back contactrelay I I4 disconnects the grid of tube I50 and the 25 discharge circuitof condenser I33 from the lower terminal of condenser I20 and connectsthe grid of tube I50 and the discharge circuit or condenser I33 over theupper front contact of relay II4, the inner lower left alternatecontacts of 30 key ST and the upper back contact of anode relay Hi tothe lower terminal of condenser I23. Tube I 50 is now prepared for respoe to the counting of the code spacing interval as determined by theinitial charged condition of condenser I23. Relay II4 also opens thesignaling circuit at its lower back contact thereby preventing thetransmission of further impulses over the signaling circuit through thecontinued oper ation' of impulsing relay I30 during the counting of thecode spacing interval. Thus, through the operation of relay I30w inconjunction with tube- I50 two impulses have been transmitted to thesignaling'circuit.

As relay I30 continues to operate and release 43 under'the control oftube I40 it causes the'periodic charging and discharging of condenserI33. but does not transmit impulses over the signaling circuit since thesignaling circuit -is open at the lower back contact of relay H4. Thedis- P charge circuit of condenser I33 may be traced over the upperfront contact of relay I30. the upper front contact of relay II4, theinner lower left alternate contacts of key ST, the upper back contact ofrelay I I1, through condenser I23, 53 negative bus-bar II8, resistanceI34 to condenser I 33. Upon each discharge of condenser I33 intocondenser I23 an increment of charge is added to the five increments ofcharge initially in condenser I23. When flve such increments have beenadded, the potential on the grid of tube I50 will be suflicientlypositive to permit tube I50 to ionize and operate anode relay III in itscathode-anode circuit. Condenser I23 discharges through tube I50.

Relay II'I upon operating functions in the manner previously describedto release relays H4, H5, H6 and I24 and to deionize tube I50. Relay I24upon releasing causes the recharging of condensers I20 and I23if key I38and start 7 key ST are still operated and the release of relay II'I.Relay III upon releasing recloses thev operating circuit of relay I24and the circuits then function in the manner previously described tocause the retransmission of impulses Gil whereby a much greater numberof calling codes may be registered and transmitted. Theoretically by theuse of two rows of digit keys it would be possible to transmit 100different codes of impulses although from a practical standpoint certaincodes which might be confused with others or which would require thetransmission of too large a number of impulses would not be used. Allapparatus and circuits of Fig. 2 which are identical to and function inthe same manner as similar apparatus and circuits of Fig. 1 have beendesignated by reference characters having the same tens and unitsdigits, but with the hundreds digits two.

' To transmit any single digit code the appropriate key in the left rowof keys is depressed followed by the operation of the start key ST tothe left. For example, if key 24l is operated to cause the transmissionof the code digit 2, the operation of key ST closes an initial chargingcircuit for condenser 220 extending from the lower terminal of thiscondenser, over the outer left back contact of relay 224, lower leftalternate contacts of key ST, contacts of key 24I to a point on thevoltage divider between resistances 2M and 205 thus charging condenser220 with eight increments of potential. Condensers 22l and 223 will alsobecome initially charged as previously described, but condenser 222 willnot be charged as no charging circuit therefor is closed. The operationof key ST also causes the delayed operation of relay 224 which opens theinitial charging circuits of the condensers and starts the transmissionof impulses in the manner previously described. Thus, a code of twoimpulses is repeatedly transmitted, each code being separated by a codespacing interval.

To transmit any two-digit code the appropriate keys in the two rows ofkeys are depressed followed by the operation of the start key ST to theright. For example, if keys 242 and 243 are operated to cause thetransmission of code 4l, the operation of key ST closes an initialcharging circuit for condenser 220 extending from the lower terminal ofthis condenser over the outer left back contact of relay 224, innerupper right alternate contacts of key ST, con tacts of key 242 to apoint on the voltage divider between resistances 206 and 201 thuscharging condenser 220 with six increments of potential. An initialcharging circuit for condenser 222 is also closed extending from thelower terminal of this condenser over the inner right back contact ofrelay 224, lower right alternate contacts of key ST, contacts of key 243to a point on the voltage divider between resistances 293 and 204 thuscharging condenser 222 with nine increments of potential. Initialcharging circuits are also effective for condensers HI and 223 thuscharging these condensers to degrees commensurate with the digitalvalues of the desired digit and code spacing intervals. The operation ofkey ST also causes the delayed operation of relay 224 which opens theinitial charging circuits of the condensers and starts the transmissionof impulses in the manner previ-' ously described.

Although the invention has been disclosed in both of its modificationsas especially adapted to a code signaling system, it will be obviousthat the invention is of much broader scope and could, with slightalterations as would be obvious to those skilled in the art, be appliedto the transmission of impulses for setting selector switches for theestablishment of telephone or other communication or signaling channels.

What is claimed is:

1. In a code calling system, a sender comprising a plurality of codekeys, a start key, an impulsing relay for transmitting series ofimpulses over a signaling circuit, a group of condensers, meanscontrolled by the operation of one of said code keys and said start keyfor charging certain of said condensers to a degree commensurate withthe numerical value of the digit or digits of a desired code number,means for charging others of said condensers to degrees commensuratewith the numerical values of digit spacing and code spacing intervalsrespectively, and means successively controlled by said condensers fordetermining the number of impulses in each series transmitted by saidrelay and the spacing of successive series of impulses.

2. In a code ca ling system, a sender comprising a plurality of codekeys, a start key, an impulsing relay for transmitting series ofimpulses over a signaling circuit, a group of condensers, meanscontrolled by the operation of a code key and said start key forcharging one of said condensers to a degree commensurate with thenumerical value of said operated code key, means for charging another ofsaid condensers to a degree commensurate with the numerical value of acode spacing interval, and means successively controlled by saidcondensers for determining the number of impulses in each seriestransmitted by said relay and the spacing of successive code series.

3. In a code calling system, a sender comprising a plurality of codekeys, a start key, an impulsing relay for transmitting series ofimpulses over a signaling circuit, a group of condensers, meanscontrolled by the operation of a code key and said start key forcharging the first and third of said condensers, respectively, todegrees commensurate with the numerical values of the two digits of acode number, means for charging the second and fourth of saidcondensers, respectively, to degrees commensurate with the numericalvalues of digit spacing and code spac ing intervals, and meanssuccessively controlled by said condensers for determining the number ofimpuses in each series of a code transmitted by said relay, the spacingof the impulse series of a code and the spacing of codes of impulseseries.

4. In a code signaling system, a sender comprising a plurality of codekeys, a start key, an impulsing relay for transmitting series ofimpulses over a signaling circuit, a group of condensers, meanscontrolled by the joint operation of two of said code keys and saidstart key for charging two of said condensers to degrees commensuratewith the numerical values of said operated code keys, respectively,means for charging others of said condensers to degrees commensuratewith the numerical values of digit spacing and code spacing intervals,respectively, and means successively controlled by said condensers fordetermining the number of impulses in each series transmitted by saidrelay and the spacing of successive series of impulses.

5. In a code calling system, a sender compri ing a plurality of codekeys, a start key having two operated positions, an impulsing relayfortransmitting series of impulses over a signaling circuit, a group ofcondensers, means controlled by the operation 01' one of said code keysand the operation of said start key to one of its positions for chargingone of said condensers to a degree commensurate with the numerical valueof said operated code key and controlled by the operation of another ofsaid code keys and the operation of said start key to its other operatedposition for charging two of said condensers to degrees commensuratewith the numerical values of two digits of a code number, respectively,means for charging others. of said condensers to degrees commensuratewith the numerical values of digit spacing and code spacing intervals,re-

spectively, and means successively controlled by said condensers fordetermining the number of impulses in each series transmitted by saidrelay and the spacing oi successive series of impulses.

6. In a code calling system a sender comprising a plurality of codekeys, a start key having two operated positions, an impulsing relay fortrans mitting series of impulses over a signaling cir-1 cult, a group ofcondensers, means controlled bythe operation of one of said code keysand the operation of said start key toone of its positions for chargingone of said condensers to a degree commensurate with the numerical valueof said operated code key, and controlled by the operation of another ofsaid code keys and the operation of said start key to its other operatedposition for charging two of said condensers to degrees commensuratewith the numerical values of two digits of the code number respectively,

means for charging others of said condensers to degrees commensuratewith the numerical values of digit spacing and code spacing intervals respectively, means successively controlled by said condensers fordetermining the number of impulses in each series transmitted by saidrelay and the spacing of successive series of impulses, and meanscontrolled in accordance with the operated position of said start keyfor determining whether a single series of impulses followed by a codespacing interval or a code of two series of impulses with an interveningg t spacing interval and a following code spacing interval will betransmitted.

- 7. In a code signaling system, a sender comprising a plurality of codekeys, a start key, 1

one of said primary condensers commensurate with the numerical value 01'said operated code key, means for applying an initial charge to anotherof said primary condensers commensurate with the numerical value 01 acode spac ing interval, and means controlled by said condensers fordetermining the number of impulses in each series transmitted by saidrelay and the spacing of successive series of impulses comprising agas-filled tube, a secondary condenser, means controlled by said relayfor periodically charging said secondary condenser and connecting itinto a discharge path, and sequence relays operable in succession inresponse to successive ionizations of said tube for successivelyconnecting said primary condensers across the discondensers acqinre thebreakdown potential of said tube.

8. In a code calling'system, a sender comprising a plurality of codekeys, a start key, an im pulsing relay for transmitting series orimpulses over a signaling circuit, a group of primary condensers, meanscontrolled by the operation oi. one of said code keys and said start keyfor charging certain of said condensers to degrees commensurate with thenumerical values of the digits 01' a desired code number, meansiorcharging others of .said condensers to degrees commensurate with thenumerical values 0! digit spacing and code spacing intervalsrespectively, means controlled by said condensers for determining thenumber of impulses in each series transmitted by said relay and thespacing of successive series of impulses comprising a gas-filled tube, asecondary condenser, means controlled by said relay for periodicallycharging said secondary condenser and" connecting it into a dischargepath,and sequence relays operable in succession in response tosuccessive ionizations of said tube for successively connecting saidprimary condensers across the discharge path or said secondary condenserand across the terr minals of said tube, whereby said tube is caused toionize and operate one of said sequence relays each time that successiveprimary condensers acquire the breakdown potential of said tube.

9. In a code calling system, a sender comprising a plurality of codekeys, a start key, an impulsing relay for transmitting series ofimpulses over a signaling circuit, a group of primary condensers, meanscontrolled by the joint operation of two oi. said code keys and saidstart key for ch r ing two of said condensers todegrees commensuratewith the numerical values of said operated code keys respectively, meansfor charging others of said condensers to degrees commensurate with thenumerical values of digit spacing and code spacing intervalsrespectively, and means controlled by said condensers for determiningthe number of impulses in each series said secondary condenser andacross the terminals of said tube, whereby said tube is caused toionizeand operate one of said sequence relays each time that successiveprimary condensers acquire the breakdown potential of said tube.

10. In a code signaling system, a sender comprising a gas-filled tubehaving a cathode, a grid and an anode, a first and a. second condenser,

a source of current, a plurality of code keys,-

a startkey, means controlled by an operated code key and said start keyfor applying from said source an initial charge to said first condensercommensurate with the numerical value of said operated code key, meansfor applying an initial charge to said second condenser commensuratewith the numerical value of a code spacing interval, a first and asecond anode relay, an operating circuit controlled overthe cathodeanodecircuit through said tube and transferable by the operation of saidfirst relay to said second relay, a locking circuit for said first relaycontrolled by said second relay, a signaling circuit extending over thenormal contacts of said first relay, a condenser discharge path acrossthe grid and cathode of said tube transferable from the first to thesecond condenser by the operation of said first relay, a thirdcondenser, and an impulsing relay periodically operable to transmitimpulses over said signaling circuit and to repeatedly charge said thirdcondenser from said source and to discharge it into said path until saidfirst condenser has accumulated a potential equal to the breakdownpotential of said tube. said first anode relay operable upon the firstbreakdown of said tube to lock under the control of said second anoderelay, to open said signaling circuit, to restore said tube and totransfer said path across said tube from said first to said secondcondenser, said second anode relayoperating when said second condenserhas accumulated a potential from the continued intermittent discharge ofsaid third condenser equal to the breakdown potential of said tube andsaid tube again breaks down, to restore said tube and to release saidfirst anode relay whereby said path across said tube is transferred fromsaid second condenser to said first condenser and said signaling circuitis again closed, said circuit functioning in this cycle until said startkey is restored.

11. In a code signaling system, a sender comprising a gas-filled tubehaving a cathode, a grid and an anode, four primary condensers, a sourceof current, a plurality of code keys, a start key, means controlled byan operated code key and said start key for applying from said sourceinitial charges to the first and third of said condensers commensuratewith the numerical values of two digits of a code number, means forapplying initial charges to the second and fourth of said condensers,respectively, commensurate with the numerical values of digit spacingand code spacing intervals, four anode relays, an operating circuitcontrolled over the cathode-anode circuit through said tube and extendedto successive ones of said relays through their operation, lockingcircuits for the first of said relays controlled by the last of saidrelays, a signaling circuit controlled over contacts of said relays, acondenser discharge path across the grid and cathode of said tubetransferable through the operation of successive ones of said relays tosuccessive ones of said condensers, a secondary condenser, and animpulsing relay periodically operable to transmit impulses over saidsignaling circuit and to repeatedly charge said secondary condenser fromsaid source and to discharge it into said path until said firstcondenser has accumulated a potential equal to the breakdown potentialof said tube, said first anode relay operable upon the first breakdownof said tube to lock under the control of the last anode relay, to opensaid signaling circuit, to restore said tube and to transfer said pathfrom said first to said second primary condensers, said second anoderelay operable when said second primary condenser has accumulated acharge equal to the breakdown potential of said tube to lock under thecontrol of the last anode relay, to close said signaling circuit, torestore said tube and to transfer said path from said second to saidthird primary condensers, said third anode relay operable when saidthird primary condenser has accumulated a charge equal to the breakdownpotential of said tube to look under the control of saidlast anoderelay, to open said signaling circuit, to restore said tube and totransfer said path from said third to said fourth primary condenser andsaid last anode relay operable when said fourth primary condenser hasaccumulated a charge equal to the breakdown potential of said tube torelease all of said anode relays whereby said path across said tube istransferred from said fourth to said first primary condenser and saidsignaling circuit is again closed, said circuit functioning in thiscycle until said start key is restored.

12. In a signaling system, a sender comprising a gas-filled tube havinga cathode, a grid and an anode, a group of primary condensers, a sourceof current, a key-set, means controlled by said key-set for applyinginitial charges to said condensers from said source commensurate withthe digits of a number, an impulsing relay, a signaling circuit,sequence relays for successively connecting said condensers in a pathacross said tube and for controlling the continuity of said signalingcircuit, a secondary condenser and means for periodically operating saidimpulsing relay to transmit impulses over said circuit and to repeatedlycharge said secondary condenser from said source and to discharge itinto said path until each primary condenser has successively accumulateda potential equal to the breakdown potential of said tube, said sequencerelays operating successively in response to successive breakdowns ofsaid tube over the cathode-anode circuit thereof.

13. In a code signaling system, a sender comprising a gas-filled tubehaving a cathode, a grid and an anode, a group of primary condensers, asource of current, a plurality of code keys, a start key, meanscontrolled by an operated code key and said start key for applyinginitial charges from said source to certain of said condenserscommensurate with the code value of said operated code key, means forapplying initial charges to other of said condensers commensurate withthe-numerical values of digit and code spacing intervals, an impulsingrelay, a signaling circuit, sequence relays for successively connectingsaid condensers in a path across said tube and for controlling thecontinuity of said signaling circuit, a secondary condenser and meansfor periodically operating said impulsing relay to transmit impulsesover said circuit and to repeatedly charge said secondary condenser fromsaid source and to discharge it into said path until each primarycondenser has successively accumulated a potential equal to thebreakdown potential of said tube, said sequence relays operatingsuccessively in response to successive breakdowns of said tube over thecathode-anode circuit thereof.

PERCY 0. SMITH.

